1. Field of the Invention
This invention relates generally to plenoptic imaging systems, and more particularly to designing plenoptic imaging systems.
2. Description of the Related Art
The plenoptic imaging system has recently received increased attention. It can be used to recalculate a different focus point or point of view of an object, based on digital processing of the captured plenoptic image. The plenoptic system also finds application in multi-modal imaging, using a multi-modal filter array in the plane of the pupil aperture. Each filter is imaged at the sensor, effectively producing a multiplexed image of the object for each imaging modality at the filter plane. Other applications for plenoptic imaging systems include varying depth of field imaging and high dynamic range imaging.
However, there is limited literature on the optical design of a plenoptic imaging system that goes beyond geometric optics considerations. Thus far, most of the literature about these systems is concentrated in the areas of computer vision, graphics and digital processing algorithms—how to further process the “light field” properties of the data captured at the sensor of a plenoptic system. These algorithms focus on what to do with the plenoptic images after they are captured. In addition, many of those algorithms are not specific to plenoptic imaging systems; they can be directly transferred to completely different configurations, such as multi-lens imaging systems (multiple cameras mounted adjacent to one another). This body of work assumes that the plenoptic imaging system has been well designed, manufactured and assembled. However, there is not much literature explaining how to actually design, manufacture or assemble plenoptic imaging systems.
As one example, consider the “focusing” a plenoptic imaging system. Much is known about how to focus a conventional imaging system, in order to produce a sharp image of the object at the sensor. However, a plenoptic imaging system that is “in focus” does not produce a sharp image of the object at the sensor array. In a plenoptic imaging system, the sensor array is not placed at a plane conjugate to the image plane. Therefore, conventional focusing criteria are not appropriate for focusing a plenoptic system. In order to design a plenoptic system, including diffraction effects, it is desirable to obtain an appropriate evaluation metric that can be used to gauge the quality of the system.
Thus, there is need for such criteria.